9 阶乘求和

//题目：求1+2!+3!+...+20!的和

public class Jiecheng {
        static long sum ,fac= 0;
        
        public static void main(String[] args) {
           long fac = 1;
           for(int i=1; i<=10; i++) {
            fac = fac * i;
            sum += fac;
           }
           System.out.println(sum);
        }
    

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